The invention relates generally to X-ray generation systems. The invention particularly relates to inverse Compton scattering X-ray generation systems.
Conventional X-ray sources generally rely on either Bremsstrahlung radiation or synchrotron radiation. In Bremsstrahlung radiation X-ray embodiments, radiation is produced when energetic electrons are decelerated by heavy solid targets made of dense, high-Z materials. For example, radiation in common medical diagnostic X-ray tubes is generally of relatively low power and comprises long pulses or a continuous wave radiation. Moreover, such radiation is randomly polarized, incoherent radiation with a broad range of energies that is not easily energy selectable or energy tunable. Where synchrotron radiation is desired, radiation is produced by ultrahigh energy electron beams passing through magnetic undulators or dipoles in a storage ring synchrotron source. The X-rays generated by the synchrotron source are generally broadband, incoherent, low energy, fixed polarization and untunable except by significant changes in undulator geometry or energy tune in a large accelerator. In addition, such sources require high energetic electron beams, which in turn require large and expensive facilities.
Delivery of hard, tunable, monochromatic X-rays in an area with geometry suitable and practical for rapid human imaging has been a long desired goal. The advantages of a tunable source of mono-energetic X-rays are well known in the medical diagnostic and non-destructive evaluation fields. A device to produce X-rays in a clinical setting should be relatively compact and capable of delivering energies that encompass the useful diagnostic imaging range. If narrow bandwidth X-rays can be tuned, one can use quite different energies for monochromatic mammography versus chest or skull imaging. By using only the frequencies best suited to the examination being performed on a patient, one eliminates a significant portion of the radiation dose delivered to that person.
Few physical processes lend themselves to production of such beams as well as the phenomenon of Inverse Compton Scattering (ICS). ICS has been successfully used to generate X-rays by using linear accelerators and large, high-powered lasers. ICS based X-ray sources, due to their coherence and spectral properties, offer significant benefits in lower dosage, higher-contrast, and better resolution over conventional X-ray tube imaging technologies.
Although tunable, mono-energetic inverse Compton scattering X-ray systems sources have been constructed and demonstrated, the major drawback to these systems is their overall size, often encompassing several large rooms. Previous designs have attempted to shrink the size of the linear accelerator section by increasing the field gradients. This is achieved by increasing the operating frequency of the linear accelerator to the high gigahertz regime. While such designs work in theory, they do not reduce to practice easily due to reliability issues associated with the very high electric fields.
Therefore there is a need for a compact, tunable, monoenergetic ICS based X-ray source.